1. Field of the Invention
The present invention relates to a process for production of a tungsten carbide-activated electrode, particularly an electrode which is utilizable as a cathode, and which consists of an electrically-conductive substrate with an active surface layer of tungsten carbide.
Electrodes of the above-mentioned type are, in general, required as cathodes during electrolysis for hydrogen generation in an acidic environment, and in particular, during electrolysis in a sulfuric acid solution, or in the cathodic formation of hydrogen or during the cathodic formation of hydrogen and the concurrent anodic oxidation of sulfur dioxide in sulfuric acid electrolytes. Particular examples are related to the electrochemical oxidation of SO.sub.2 from waste gases during H.sub.2 production, as well as the analogous electrolysis in the sulfuric acid-hybrid continuous cycle process.
2. Discussion of the Prior Art
A known process for the production of tungsten carbide-activated electrodes consists of the initial preparation of tungsten carbide and applying the latter in the form of a powder by means of a binding agent (polyimide or polysulfone) onto the substrate. However, the electrodes which are produced in this manner fail to exhibit a sufficiently high electrochemical activity.
Furthermore, another process is known according to which there can be produced cathodes imparted with a sufficiently high electrochemical activity (P. Cavallotti in Hydrogen as an Energy Vector, edited by A.A. Strub and G. Imarisio, D. Reidel Publishing Company, Dordrecht/Boston/London, 1980, p. 408, EUR 6783). Pursuant to this known process, a tungsten carbide-teflon binder layer is applied onto a gold-coated substrate. Nevertheless, this type of process is extremely expensive due to the utilization of the noble metal.
Another known process for the production of a tungsten carbide-activated electrode consists in the cold-pressing of active tungsten carbide together with graphite powder into the electrode (H. Bohm, Chem.-Ing.-Techn. 49 (1977, 328). The thusly produced cathodes provide only relatively low cathodic current densities, which leads to the conclusion that the electrodes possess an unsatisfactory grain structure.